JP2007162493A - Compression expansion turbine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compression expansion turbine system capable of improving efficiency drop caused by sealing performance, improving long term durability of a rolling bearing and performing stable control by a controller of a simple structure. <P>SOLUTION: This compression expansion turbine system uses the rolling bearings 15, 16 and a magnetic bearing in parallel. A compressor side impeller 7a is driven by power generated by a turbine side impeller 7a. Stiffness value of a compound spring formed by the rolling bearings 15, 16 and a support system of the rolling bearings is established to keep a relation that the same is larger than negative stiffness value of an electromagnet 17. Sleeves 21A, 22A to be non-contact seals elastically supported by elastic support support members 21B, 22B are provided between the compressor side impeller 6a and the bearing 15 near the same, and between the turbine side impeller 7a and the bearing 16 near the same. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a compression / expansion turbine system of an air cycle refrigeration cooling system in which air is used as a refrigerant and is used in a refrigeration warehouse, a low-temperature room below zero degrees, air conditioning, and the like.

  Since the air cycle refrigeration cooling system uses air as a refrigerant, energy efficiency is insufficient as compared with the case where chlorofluorocarbon, ammonia gas, or the like is used. In addition, in facilities where refrigerant air can be directly blown into, such as a refrigerated warehouse, the total cost may be reduced by omitting the internal fan and defrost, etc. In such applications, the air cycle refrigeration cooling system Has been proposed (for example, Patent Document 1).

Further, it is known that the theoretical efficiency of air cooling is equal to or higher than that of Freon or ammonia gas in a deep coal region of -30 ° C to -60 ° C. However, it is also stated that obtaining the theoretical efficiency of the air cooling is not possible until there is an optimally designed peripheral device. The peripheral device is a compressor, an expansion turbine, or the like.
As the compressor and the expansion turbine, a turbine unit in which a compressor impeller and an expansion turbine impeller are attached to a common main shaft is used (Patent Document 1).

In addition, as a turbine compressor which processes process gas, a turbine impeller is attached to one end of the main shaft, a compressor impeller is attached to the other end, and the main shaft is supported by a journal and a thrust bearing that is controlled by an electromagnet current. A compressor has been proposed (Patent Document 2).
In addition, although it is a proposal for a gas turbine engine, in order to avoid the thrust load acting on the rolling bearing for supporting the main shaft from shortening the bearing life, the thrust load acting on the rolling bearing should be reduced by the thrust magnetic bearing. Has been proposed (Patent Document 3).
Japanese Patent No. 2623202 Japanese Patent Application Laid-Open No. 7-91760 JP-A-8-261237

As described above, as the air cycle refrigeration cooling system, in order to obtain the theoretical efficiency of air cooling that is highly efficient in the deep coal region, an optimally designed compressor and expansion turbine are required.
As the compressor and the expansion turbine, a turbine unit in which the compressor wheel and the expansion turbine wheel are attached to a common main shaft as described above is used. In this turbine unit, the compressor impeller can be driven by the power generated by the expansion turbine, thereby improving the efficiency of the air cycle refrigerator.

However, in order to obtain practical efficiency, it is necessary to keep the gap between each impeller and the housing minute. The fluctuation of the gap hinders stable high-speed rotation and causes a decrease in efficiency.
In addition, a thrust force acts on the main shaft by the air acting on the compressor impeller and the turbine impeller, and a thrust load is applied to the bearing that supports the main shaft. The rotation speed of the main shaft of the turbine unit in the air cycle refrigeration cooling system is 80,000 to 100,000 rotations per minute, which is very high compared with a bearing for general use. For this reason, the thrust load as described above causes a decrease in long-term durability and life of the bearing supporting the main shaft, and decreases the reliability of the turbine unit for air cycle refrigeration cooling. Unless such a problem of long-term durability of the bearing is solved, it is difficult to put the air cycle refrigeration cooling turbine unit into practical use. However, the technique disclosed in Patent Document 1 has not yet been solved for the deterioration of the long-term durability of the bearing against the load of the thrust load under the high-speed rotation.

  In the case where the main shaft is supported by a journal bearing made of a magnetic bearing and a thrust bearing, such as the magnetic bearing type turbine compressor of Patent Document 2, the journal bearing does not have a restriction function in the axial direction. Therefore, if there is an unstable factor in controlling the thrust bearing, it is difficult to perform stable high-speed rotation while maintaining a minute gap between the impeller and the diffuser. In the case of a magnetic bearing, there is also a problem of contact when the power is stopped.

Accordingly, the inventors of the present invention have proposed a compression / expansion turbine unit for air cycle refrigeration cooling having a structure as shown in FIG. 12 as a means for solving the above problems (Japanese Patent Application No. 2005-239464). In this turbine unit, a roller wheel 65a for the compressor 56 and a turbine wheel 57a for the expansion turbine 57 are attached to both ends of the main shaft 63, and grease lubricated rolling bearings 65 and 66 are used as bearings for rotatably supporting the main shaft 63. In combination with an electromagnet 67 constituting a magnetic bearing, the rolling bearings 65 and 66 support a radial load, the magnetic bearing supports an axial load, and the electromagnet 67 is a thrust plate 63a provided perpendicularly and coaxially to the main shaft 63. The electromagnet 67 is controlled by the controller 69 in accordance with the output of the sensor 68 that detects the force in the axial direction.
In addition, a portion in the compressor side casing 56b that constitutes the compressor 56 with the compressor impeller 56a and a portion on the compressor impeller 56a side with respect to the rolling bearing 65, and a rolling in the turbine side casing 57b that constitutes the expansion turbine 57 with the turbine impeller 57a. The portions closer to the turbine impeller 57a than the bearing 66 are formed with inner diameter surfaces close to the main shaft 63, and non-contact seals 71 and 72 are formed on these inner diameter surfaces. The non-contact seals 71 and 72 are labyrinth seals or thread groove seals formed by arranging a plurality of circumferential grooves in the axial direction on the inner diameter surfaces of the casings 56b and 57b.

  However, in the turbine unit configured as described above, when the non-contact seals 71 and 72 are labyrinth seals, it is difficult to rotate the main shaft 63 at a high speed while keeping the seal gap 10 μm or less. Therefore, in order to avoid contact between the seal fin and the main shaft 63, when the seal gap is widened, due to the pressure difference between the compressor 56 side and the expansion turbine 57 side, the inside of each rolling bearing 65, 66 or each rolling bearing 65, 66. There is a problem in that air leaks from the contact surfaces between the casings 56b and 57b and the efficiency of the turbine unit decreases. Further, the grease in the rolling bearings 65 and 66 is dried and scattered by the passing air, and the long-term durability of the rolling bearings 65 and 66 is also reduced.

  An object of the present invention is to provide a compression / expansion turbine system that can improve efficiency reduction due to sealing performance, improve the long-term durability of a rolling bearing, and can be stably controlled with a controller having a simple configuration. It is.

  A compression / expansion turbine system according to a first aspect of the present invention uses a rolling bearing and a magnetic bearing in combination, the rolling bearing supports a radial load, and the magnetic bearing supports one or both of an axial load and a bearing preload. The electromagnet of the magnetic bearing is attached to the spindle housing so as to face a flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft in a non-contact manner, and the compressor side impeller and the turbine side impeller include the thrust side A compressor-side impeller is driven by the power generated by the turbine-side impeller, which is fitted to the main shaft common to the plate, and has a controller that controls the electromagnet according to the output of the sensor that detects the axial force. The stiffness value of the composite spring formed by the rolling bearing and the support system of the rolling bearing is the negative stiffness of the electromagnet. The compression / expansion turbine unit housing is composed of a spindle housing, a rolling bearing support, a turbine side casing, and a compressor side casing, between the compressor side impeller and the nearby bearings. Alternatively, a non-contact seal that is elastically supported by the housing of the compression / expansion turbine unit and forms a seal gap on the outer periphery of the main shaft is provided between the turbine side impeller and the bearing in the vicinity thereof.

According to this configuration, since the non-contact seal is elastically supported between the compressor side wheel and the nearby bearing, or between the turbine side wheel and the nearby bearing, excellent sealing performance is achieved. Is obtained. That is, the non-contact seal is made of, for example, a sleeve and is elastically supported by the elastic support member. Therefore, the non-contact seal made of a sleeve or the like can move in the radial direction within the elastic deformation range of the elastic support member, and the non-contact seal made of the sleeve or the like and the main shaft constitute a so-called circular bearing. It is possible to follow the swing of the main shaft. By improving the sealing performance in this way, it is possible to reduce air leakage in the rolling bearing due to the pressure difference between the compressor side and the turbine side, or from the contact surface between the rolling bearing and the bearing support portion. The efficiency reduction of the unit can be improved. Further, since the grease does not dry or scatter in the rolling bearing due to the passing air, the long-term durability of the rolling bearing can be improved.
In addition, since the stiffness value of the composite spring formed by the rolling bearing and the support system of the rolling bearing is set to be larger than the negative stiffness value of the electromagnet portion, the mechanical system of the mechanical system is controlled in the control band. The phase can be prevented from being delayed by 180 °, the controlled object can be made stable, and stable control can be performed even if the circuit configuration of the controller is simple such as proportional or proportional integration.

A compression / expansion turbine system according to a second aspect of the present invention uses a rolling bearing and a magnetic bearing in combination, the rolling bearing supports a radial load, and the magnetic bearing supports one or both of an axial load and a bearing preload. The electromagnet of the magnetic bearing is attached to the spindle housing so as to face the flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft in a non-contact manner. The compressor side impeller, the turbine side impeller, and the motor rotor are The main shaft is fitted to the common main shaft with the thrust plate, the motor rotor is disposed between the rolling bearings on both sides, the motor stator is disposed to face the motor rotor, and the main shaft is driven by magnetic force or Lorentz force from the motor stator. According to the output of the sensor that detects the force in the axial direction. Having a controller for controlling the support force of the magnet, the stiffness value of the composite spring formed by the rolling bearing and the support system of the rolling bearing is a negative stiffness value of the composite spring formed by the electromagnet and the motor The compression expansion turbine unit housing is composed of a spindle housing, a motor housing, a rolling bearing support, a turbine side casing, and a compressor side casing, and the compressor side impeller and bearings in the vicinity thereof. Or a non-contact seal that is elastically supported by the housing of the compression / expansion turbine unit to form a seal gap on the outer periphery of the main shaft between the turbine side impeller and the bearing in the vicinity thereof. To do.
Also in this case, similarly to the first invention, it is possible to improve efficiency reduction due to the sealing performance and to improve the long-term durability of the rolling bearing.
Further, the stiffness value of the synthetic spring formed by the rolling bearing and the rolling bearing support system is set to be larger than the negative stiffness value of the synthetic spring formed by the electromagnet portion and the motor portion. Therefore, in the control band, the phase of the mechanical system can be prevented from being delayed by 180 °, the controlled object can be stabilized, and the controller circuit configuration can be controlled with a simple configuration such as proportional or proportional integration. Can be done.

  In these first and second inventions, an O-ring may be used as an elastic support member that elastically supports the non-contact seal on the housing of the compression / expansion turbine unit. When an O-ring is used as the elastic support member, the effect of elastically supporting the non-contact seal so as to be able to follow the swing of the main shaft can be obtained satisfactorily.

In each configuration, the non-contact seal may be a sleeve. By using a sleeve, an appropriate bearing gap that can be sealed without contact can be easily obtained. In addition, by using a non-contact seal as a sleeve, the sleeve and the main shaft can form a so-called circular bearing, and the follow-up property of the non-contact seal to the swing of the main shaft is excellent.
The sleeve forming the non-contact seal may be made of carbon, a copper alloy, or pure copper. When the sleeve is made of carbon, copper alloy, or pure copper, even if the steel main shaft comes into contact, the main shaft is not damaged, and some contact is allowed.

In this invention, the compression / expansion turbine system may compress the inflow air by a compressor of the turbine unit, cooling by another heat exchanger, adiabatic expansion by the expansion turbine of the turbine unit, compression by pre-compression means, heat It may be used in an air cycle refrigeration cooling system that sequentially performs cooling by an exchanger, compression by a compressor of a turbine unit, cooling by another heat exchanger, and adiabatic expansion of the turbine unit by an expansion turbine.
When the compression / expansion turbine system is applied to such an air cycle refrigeration / cooling system, in the compression / expansion turbine system, a stable high-speed rotation of the main shaft can be obtained while maintaining an appropriate clearance of each impeller, and the bearing has a long-term durability. Therefore, the reliability is improved as a whole of the compression / expansion turbine system and, as a whole, the air cycle refrigeration cooling system. In addition, stable high-speed rotation, long-term durability, and reliability of the main shaft bearing of the compression / expansion turbine system, which is the bottleneck of the air cycle refrigeration cooling system, improve the practical use of the air cycle refrigeration cooling system. .

  A compression / expansion turbine system according to a first aspect of the present invention uses a rolling bearing and a magnetic bearing in combination, the rolling bearing supports a radial load, and the magnetic bearing supports one or both of an axial load and a bearing preload. The electromagnet of the magnetic bearing is attached to the spindle housing so as to face a flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft in a non-contact manner, and the compressor side impeller and the turbine side impeller include the thrust side A compressor-side impeller is driven by the power generated by the turbine-side impeller, which is fitted to the main shaft common to the plate, and has a controller that controls the electromagnet according to the output of the sensor that detects the axial force. The stiffness value of the composite spring formed by the rolling bearing and the support system of the rolling bearing is the negative stiffness of the electromagnet. The compression / expansion turbine unit housing is composed of a spindle housing, a rolling bearing support, a turbine side casing, and a compressor side casing, between the compressor side impeller and the nearby bearings. Or a non-contact seal that is elastically supported by the housing of the compression / expansion turbine unit and forms a seal gap on the outer periphery of the main shaft between the turbine side impeller and the bearing in the vicinity thereof. It is possible to improve the drop, improve the long-term durability of the rolling bearing, and perform stable control with a controller having a simple configuration.

  A compression / expansion turbine system according to a second aspect of the present invention uses a rolling bearing and a magnetic bearing in combination, the rolling bearing supports a radial load, and the magnetic bearing supports one or both of an axial load and a bearing preload. The electromagnet of the magnetic bearing is attached to the spindle housing so as to face the flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft in a non-contact manner. The compressor side impeller, the turbine side impeller, and the motor rotor are The main shaft is fitted to the common main shaft with the thrust plate, the motor rotor is disposed between the rolling bearings on both sides, the motor stator is disposed to face the motor rotor, and the main shaft is driven by magnetic force or Lorentz force from the motor stator. According to the output of the sensor that detects the force in the axial direction. The controller has a controller for controlling the support force of the magnet, and the stiffness value of the combined spring formed by the rolling bearing and the support system of the rolling bearing is the negative stiffness of the combined spring formed by the electromagnet and the motor unit. The compression expansion turbine unit housing is composed of a spindle housing, a motor housing, a rolling bearing support, a turbine side casing, and a compressor side casing, and the compressor side impeller and the vicinity thereof A non-contact seal that is elastically supported by the housing of the compression / expansion turbine unit and forms a seal gap on the outer periphery of the main shaft is provided between the bearings or between the turbine side impeller and the bearings in the vicinity thereof. This reduces the efficiency drop caused by rolling, improves the long-term durability of rolling bearings, and has a simple configuration. Stable control can be performed in the controller.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a cross-sectional view of a compression / expansion turbine unit 5 constituting the compression / expansion turbine system of this embodiment. The compression / expansion turbine unit 5 includes a compressor 6 and an expansion turbine 7. A compressor impeller 6 a of the compressor 6 and a turbine impeller 7 a of the expansion turbine 7 are respectively attached to both ends of the main shaft 13. Further, the compressor impeller 6a is driven by the power generated in the turbine impeller 7a, and no other drive source is provided.

The housing 12 of the compression / expansion turbine unit 5 is composed of a compressor-side casing 6b, a spindle housing 14, a rolling bearing support portion 20 interposed between the compressor-side casing 6b and the spindle housing 14, and a turbine-side casing 7b. Configured.
In FIG. 1, the compressor 6 is composed of a compressor impeller 6a and the compressor casing 6b facing the compressor impeller 6a with a minute gap d1 and sucked in the axial direction from the suction port 6c at the center. The air is compressed by the compressor wheel 6a and discharged from the outlet (not shown) at the outer peripheral portion as indicated by the arrow 6d.
The expansion turbine 7 is composed of a turbine impeller 7a and a turbine casing 7b opposed to the turbine impeller 7a via a minute gap d2, and the air sucked from the outer periphery as indicated by an arrow 7c The vehicle 7a adiabatically expands and discharges in the axial direction from the central outlet 7d.

  In this compression / expansion turbine unit 5, the main shaft 13 is supported by a plurality of rolling bearings 15 and 16 in the radial direction, and either or both of the axial load and the bearing preload applied to the main shaft 13 are supported by an electromagnet 17 that is a magnetic bearing. It is supposed to be. The compression / expansion turbine unit 5 includes a sensor 18 that detects an axial load acting on the rolling bearing 16, and a magnetic bearing controller 19 that controls the supporting force of the electromagnet 17 according to the output of the sensor 18. is doing. The electromagnet 17 is installed in the spindle housing 14 so as to face the both surfaces of a flange-like thrust plate 13a made of a ferromagnetic material that is provided in the center of the main shaft 13 as a unitary structure perpendicular to and coaxial with the main shaft 13 in a non-contact manner. The thrust plate 13a is an electromagnet target. The material of the main shaft 13 is low carbon steel with good magnetic properties.

  The rolling bearings 15 and 16 that support the main shaft 13 have a function of restricting the position in the axial direction. For example, deep groove ball bearings or angular ball bearings are used. In the case of a deep groove ball bearing, it has a thrust support function in both directions, and has the effect of returning the axial position of the inner and outer rings to the neutral position. These two rolling bearings 15 and 16 are disposed near the compressor impeller 6a and the turbine impeller 7a in the unit housing 12, respectively.

  The main shaft 13 is a stepped shaft having a large diameter portion 13c at the center and small diameter portions 13d at both ends. The bearings 15 and 16 on both sides have their inner rings 15a and 16a fitted into the small diameter portion 13d in a press-fit state, and one of the width surfaces engages with a stepped surface between the large diameter portion 13c and the small diameter portion 13d. Further, a through-hole (not shown) provided in the central portion of the compressor impeller 6a and the turbine impeller 7a is fitted into the small diameter portions 13d at both ends of the main shaft 13 in a press-fitted state, so that the compressor impeller 6 a and a turbine impeller 7 a are attached to the main shaft 13.

  The sensor 18 is provided on the stationary side in the vicinity of the rolling bearing 16 on the turbine impeller 7a side, that is, on the spindle housing 14 side. The rolling bearing 16 provided with the sensor 18 in the vicinity thereof has an outer ring 16 b fitted in the bearing housing 23 in a fixed state. The bearing housing 23 has an inner flange 23a that is formed in a ring shape and engages with the width surface of the outer ring 16b of the bearing 16 at one end, and is movable in the axial direction on an inner diameter surface 24 provided on the spindle housing 14. It is mated. The inner collar 23a is provided at the center side end in the axial direction.

  The sensors 18 are distributed and arranged at a plurality of circumferential locations (for example, two locations) around the main shaft 13, a width surface on the inner flange 23 a side of the bearing housing 23, and one electromagnet 17 that is a member fixed to the spindle housing 14. It is interposed between. The sensor 18 is applied with preload by a sensor preload spring 25. The sensor preload spring 25 is housed in a housing recess provided in the turbine-side casing 7 b and biases the outer ring 16 b of the rolling bearing 16 in the axial direction. The sensor preload spring 25 is moved through the outer ring 16 b and the bearing housing 23. Preload. The sensor preload spring 25 is composed of, for example, coil springs provided at a plurality of locations in the circumferential direction around the main shaft 13.

  The preload by the sensor preload spring 25 is to enable the sensor 18 that detects the thrust force by the pressing force to detect any movement of the main shaft 13 in the axial direction. The magnitude is greater than the average thrust force acting on the main shaft 13 in a normal operating state.

  The rolling bearing 15 on the non-arrangement side of the sensor 18 is installed so as to be movable in the axial direction with respect to the rolling bearing support portion 20, and is elastically supported by a bearing preload spring 26. In this example, the outer ring 15b of the rolling bearing 15 is fitted to the inner diameter surface of the rolling bearing support 20 so as to be movable in the axial direction, and the bearing preload spring 26 is interposed between the outer ring 15b and the compressor side casing 6b. ing. The bearing preload spring 26 biases the outer ring 15b so as to oppose the step surface of the main shaft 13 with which the width surface of the inner ring 15a is engaged, and applies preload to the rolling bearing 15. The bearing preload spring 26 includes coil springs and the like provided at a plurality of locations in the circumferential direction around the main shaft 13 and is accommodated in the accommodating recesses provided in the compressor side casing 6b. The bearing preload spring 26 has a smaller spring constant than the sensor preload spring 25.

Between the compressor impeller 6a and the rolling bearing 15 in the vicinity thereof, and between the turbine impeller 7a and the rolling bearing 16 in the vicinity thereof, an inner diameter surface is formed to have a diameter close to the main shaft 13, respectively. Non-contact seals comprising sleeves 21A and 21B that form seal gaps on the outer periphery are arranged. A non-contact seal is also called a gap seal.
The sleeve 21A, which is a non-contact seal on the compressor impeller 6a side, is elastically formed on the inner diameter surface of the portion 6ba adjacent to the rolling bearing 15 in the compressor side casing 6b as shown in FIG. The support member 21B is elastically supported so as to be displaceable in the radial direction. A groove 50 is formed at the axially intermediate position of the outer diameter surface of the sleeve 21A, and a groove 51 is also formed on the inner diameter surface of the bearing adjacent portion 6ba of the compressor side casing 6b facing the groove 50. The elastic support member 21 </ b> B is engaged over 50 and 51.
The sleeve 22A which is a non-contact seal on the turbine impeller 7a side is also elastically formed on the inner diameter surface of the portion 7ba adjacent to the rolling bearing 16 in the turbine side casing 7b as shown in FIG. The support member 22B is elastically supported so as to be movable in the radial direction. A groove 52 is formed at the axially intermediate position of the outer diameter surface of the sleeve 22A, and a groove 53 is also formed on the inner diameter surface of the bearing adjacent portion 7ba of the turbine side casing 7b facing the groove 52. The elastic support member 22 </ b> B is engaged over 52 and 53.

The seal gap between the sleeves 21A, 22A and the main shaft 13 is preferably 15 μm or less, and if it is 10 μm or less, there is almost no air leakage in the gap. Each sleeve 21A, 22A is made of carbon or a copper alloy (including pure copper), and some contact between the main shaft 13 and the sleeves 21A, 22A is allowed.
Here, the support portions of the sleeves 21A and 22A serving as the non-contact seals are the compressor side casing 6b and the turbine side casing 7b. However, depending on the structure of the unit housing 12, the sleeve 21A on the compressor impeller 6a side may be provided. The sleeve 22A on the turbine impeller 7a side may be supported by the inner diameter surface of the rolling bearing support portion 20 and the inner diameter surface of the spindle housing 14, respectively. Further, the non-contact seal constituted by the sleeves 21 and 22A may be applied only to the compressor impeller 6a side or only to the turbine impeller 7a side.

  A gap 27 for restricting heat inflow from the compressor side casing 6b to the rolling bearing support portion 20 is formed on a surface where both end surfaces of the compressor side casing 6b and the rolling bearing support portion 20 on the compressor 6 side are coupled. . In this embodiment, a protrusion 20a is formed on the outer diameter side of the end face of the rolling bearing support portion 20, and the gap 27 is formed by surface contact or point contact of the protrusion 20a with the compressor side casing 6b. A protrusion may be formed on the end surface of the side casing 6b. The protrusions 20a may be formed in a ring shape over the entire circumference in the circumferential direction, or may be formed by being intermittently distributed in the circumferential direction.

  A cooling path 28 for cooling the unit housing 12 is formed in the vicinity of the gap 27 in the rolling bearing support portion 20. The cooling path 28 may be formed in the compressor side casing 6b. Water, oil, or air is used as a cooling medium flowing through the cooling path 28. In this way, by configuring a cooling system that allows the cooling medium to flow through the cooling path 28, the temperature of the rolling bearing support 20, and further the temperature of the rolling bearing 15, is an appropriate temperature that is equal to or lower than the allowable temperature of the rolling bearing 15 to be used. Controlled.

The dynamic model of the magnetic bearing device in the compression / expansion turbine unit 5 can be constituted by a simple spring system. That is, in this spring system, a combined spring composed of the rolling bearings 15 and 16 and a support system for these bearings (sensor preload spring 25, bearing preload spring 26, bearing housing 23, etc.) and a spring of the electromagnet 17 are arranged in parallel. This is the configuration. In this spring system, the composite spring constituted by the rolling bearings 15 and 16 and the support system of these bearings has rigidity acting in proportion to the amount of displacement in the direction opposite to the displaced direction, whereas the electromagnet 17. This spring has a negative stiffness that acts in proportion to the amount of displacement in the displaced direction.
For this reason, the magnitude relationship between the stiffness of the composite spring and the negative stiffness of the spring of the electromagnet 17 is
Synthetic spring stiffness <electromagnet negative stiffness (1)
In this case, the phase of the mechanical system is delayed by 180 ° and becomes an unstable system. Therefore, in the magnetic bearing controller 19 for controlling the electromagnet 17, it is necessary to add a phase compensation circuit in advance. It becomes complicated.

Therefore, in this embodiment, the magnitude relationship between the stiffness of the composite spring and the negative stiffness of the spring of the electromagnet 17 is as follows.
Rigidity value of synthetic spring> Negative stiffness value of electromagnet (2)
It is said. As a result, the phase of the mechanical system can be prevented from being delayed by 180 ° in the control band, so that the control target of the controller 19 can be stabilized, and the circuit configuration of the controller 19 is proportional or proportional to integral as shown in FIG. Easy to configure.
In the controller 19 of FIG. 3 shown in the block diagram, the detection outputs P1 and P2 of each sensor 18 are adjusted by the sensor output calculation circuit 31, and the calculation result is compared with the target value of the reference value setting means 33 by the comparator 32. The control signal of the electromagnet 17 is calculated by performing a proportional integration (or proportional) process that is appropriately set according to the compression / expansion turbine unit 5 by the PI compensation circuit (or P compensation circuit) 34. Is calculated. The output of the PI compensation circuit (or P compensation circuit) 34 is input to power circuits 37 and 38 that drive the electromagnets 17 ₁ and 17 ₂ in each direction via diodes 35 and 36. The electromagnets 17 ₁ and 17 ₂ are a pair of electromagnets 17 facing the thrust plate 13a shown in FIG. 1, and only the attractive force acts. Therefore, the direction of current is determined in advance by the diodes 35 and 36, and the two electromagnets 17 ₁ and 17 ₂ are selectively driven.

The compression / expansion turbine unit 5 having this configuration is applied to, for example, an air cycle refrigeration cooling system so that air serving as a cooling medium can be efficiently exchanged by a heat exchanger (not shown here) at a subsequent stage. Then, the air cooled by the heat exchanger and cooled by the heat exchanger at the subsequent stage is cooled and discharged by adiabatic expansion to a target temperature, for example, a very low temperature of about −30 ° C. to −60 ° C., by the expansion turbine 7. Used to be.
In such a use example, the compressor-expansion turbine unit 5 has the compressor impeller 6a and the turbine impeller 7a attached to the common main shaft 13, and the compressor impeller 6a is driven by the power generated by the turbine impeller 7a.

  In this way, in the compression / expansion turbine system of this embodiment configured as the compression / expansion turbine unit 5, between the compressor impeller 6a and the rolling bearing 15 in the vicinity thereof, or between the turbine impeller 7a and the rolling bearing 16 in the vicinity thereof. Since the sleeves 21A and 22A serving as non-contact seals that are elastically supported are provided between them, excellent sealing performance can be obtained. Specifically, the sleeves 21A and 22A can move in the radial direction within the elastic deformation range of the elastic support members 21B and 22B, and the sleeves 21A and 22A and the main shaft 13 constitute a perfect circle bearing. The sleeves 21A and 22A can follow the swinging movement of the main shaft 13. By improving the sealing performance in this way, the rolling bearings 15 and 16 due to the pressure difference between the compressor 6 side and the expansion turbine 7 side, or the rolling bearings 15 and 16 and the bearing support portion (the rolling bearing support portion 20 and the spindle housing). 14) The air leakage from the contact surface with 14) can be reduced, and the efficiency reduction of the compression / expansion turbine unit 5 can be improved. Further, since the grease is not dried or scattered by the rolling bearings 15 and 16 due to the passing air, the long-term durability of the rolling bearings 15 and 16 can be improved.

  Further, in this embodiment, the compressor impeller 6a and the turbine impeller 7a are fitted to the main shaft 13 common to the thrust plate 13a, and the compression / expansion for driving the compressor impeller 6a by the power generated in the turbine impeller 7a. In the compression / expansion turbine unit 5 constituting the turbine system, the magnetic bearing device having the above-described configuration is applied to support the main shaft 13, so that the stable high speed of the main shaft 13 is maintained while maintaining appropriate gaps d 1 and d 2 between the impellers 6 a and 7 a. The rotation is obtained, and the long-term durability and the life of the rolling bearings 15 and 16 are improved.

  That is, in order to ensure the compression and expansion efficiency of the compression / expansion turbine unit 5, it is necessary to keep the gaps d1 and d2 between the impellers 6a and 7a and the casings 6b and 7b minute. For example, when this compression / expansion turbine unit 5 is applied to an air cycle refrigeration cooling system, ensuring this efficiency is important. On the other hand, since the main shaft 13 is supported by the rolling bearings 15 and 16, the axial position of the main shaft 13 is regulated to some extent by the restriction function of the axial position of the rolling bearing, and the impellers 6a and 7a and the housing 6b. , 7b can be kept constant.

However, a thrust force is applied to the main shaft 13 of the turbine unit 5 by the pressure of air acting on the impellers 6a and 7a. Further, the turbine unit 5 used in the air cooling system rotates at a very high speed of about 80,000 to 100,000 rotations per minute, for example. Therefore, when the thrust force acts on the rolling bearings 15 and 16 that rotatably support the main shaft 13, the long-term durability of the rolling bearings 15 and 16 is reduced.
In this embodiment, since the thrust force is supported by the electromagnet 17, the thrust force acting on the rolling bearings 15 and 16 for supporting the main shaft 13 can be reduced while suppressing an increase in torque without contact. In this case, since the sensor 18 for detecting the thrust force acting on the rolling bearing 16 and the magnetic bearing controller 19 for controlling the supporting force by the electromagnet 17 according to the output of the sensor 18 are provided, the rolling bearings 15 and 16 are provided. Can be used in an optimum state against the thrust force according to the bearing specifications.

  4 and 5 show another embodiment of the present invention. In the compression / expansion turbine system of this embodiment, O-rings are used as the elastic support members 21B and 22B of the sleeves 21A and 22A which are non-contact seals in the first embodiment shown in FIG. 5A shows an enlarged cross-sectional view of the non-contact seal 21 on the compressor impeller 6a side, and FIG. 5B shows an enlarged cross-sectional view of the non-contact seal 22 on the turbine impeller 7a side. Other configurations are the same as those in the first embodiment. In this case, the inner diameters of the elastic support members 21B and 22B made of O-rings are made equal to or smaller than the inner diameters of the grooves 50 and 52 of the sleeves 21A and 22A, and the elastic support members 21B and B made of O-rings in the grooves 50 and 52 of the sleeves 21A and 22A. 22B is in close contact. Further, the outer diameters of the elastic support members 21B and 22B made of O-rings are set to be equal to or smaller than the outer diameters of the bottom portions of the grooves 51 and 53 of the bearing adjacent portions 6ba and 7ba in the casings 6b and 7b. The sleeves 21A and 22A can be moved in the radial direction.

  Also in this case, since the sleeves 21A and 22A and the main shaft 13 constitute a perfect circle bearing, the sleeves 21A and 22A can follow the swing of the main shaft 13. Further, due to the pressure difference generated between the compressor 6 side and the expansion turbine 7 side when the main shaft 13 rotates, the sleeves 21A and 22A move in the axial direction and protrude from the outer diameter surfaces of the sleeves 21A and 22A. The portions of the elastic support members 21B and 22B made of an O-ring are in contact with the end surfaces of the grooves 51 and 53 of the bearing adjacent portions 6ba and 7ba in the casings 6b and 7b. Thereby, the sealing performance by sleeve 21A, 22A used as a non-contact seal and elastic support member 21B, 22B is ensured.

  6 and 7 show still another embodiment of the present invention. In the compression / expansion turbine system of this embodiment, in the first embodiment shown in FIG. 1, between the compressor impeller 6a and the rolling bearing 15 in the vicinity of the small diameter portion 13d of the main shaft 13, and the turbine impeller 7a and its By interposing ring-shaped rolling bearing retainer members 54 and 55 between the adjacent rolling bearings 16, the inner diameter surfaces of the sleeves 21 A and 22 A and the outer diameter surfaces of the rolling bearing retainer members 54 and 55 are not. A seal gap of the contact seal is formed. The rolling bearing pressing members 54 and 55 are fitted into the small diameter portion 13d of the main shaft 13 in a press-fitted state. Other configurations are the same as those in the first embodiment.

  As described above, since the material of the main shaft 13 is made of low carbon steel, the outer diameter surface of the main shaft 13 is scratched when the rolling bearings 15 and 16 are inserted and removed. In the embodiment shown in FIG. May affect the sealing performance. In the case of this embodiment, the outer diameter surface of the small diameter portion 13d of the main shaft 13 is covered with the rolling bearing retainer members 54 and 55, and the outer diameter surfaces of the rolling bearing retainer members 54 and 55 and the inner diameter surfaces of the sleeves 21A and 22A are sealed. Since the gap is formed, there is no deterioration in the sealing performance due to the scratch on the outer diameter surface of the main shaft 13, the inside of the rolling bearings 15, 16 due to the pressure difference between the compressor 6 side and the expansion turbine 7 side, the rolling bearing 15, Air leakage from the contact surface between the bearing 16 and the bearing support (the rolling bearing support 20 or the spindle housing 14) can be reduced, and the efficiency reduction of the compression / expansion turbine unit 5 can be improved.

  8 and 9 show still another embodiment of the present invention. In the compression / expansion turbine system of this embodiment, in the first embodiment shown in FIG. 1, the main shaft 13 is supported by rolling bearings 15 and 16 and an electromagnet 17 as a magnetic bearing, and the main shaft 13 is driven to rotate. The motor 39 is provided. The motor 39 is controlled by the motor controller 29 independently of the electromagnet 17.

  The electromagnet 17 is provided on each surface of two flange-shaped thrust plates 13a and 13b made of a ferromagnetic material provided as an integral structure perpendicular to and coaxially with the main shaft 13 so as to be aligned in the axial direction at the axial intermediate portion of the main shaft 13. A pair is installed in the spindle housing 14 so as to face each other without contact. Specifically, one of the electromagnets 17 constituting the magnetic bearing unit is opposed to this one surface in a non-contact manner with the one surface facing the expansion turbine 7 of the thrust plate 13a located near the expansion turbine 7 as an electromagnet target. Installed in the spindle housing 14. Further, the other electromagnet 17 constituting the magnetic bearing unit has one surface facing the compressor 6 side of the thrust plate 13b located near the compressor 6 as an electromagnet target, and faces the spindle housing 14 so as to face this one surface in a non-contact manner. Installed.

The motor 39 is a motor unit including a motor rotor 39a provided on the main shaft 13 along with the electromagnet 17, and a motor stator 39b facing the motor rotor 39a in the axial direction. Specifically, the motor rotor 39a that constitutes one part of the motor unit is arranged on each side of the main shaft 13 opposite to the side where the electromagnets 17 of the thrust plates 13a and 13b face each other at an equal pitch in the circumferential direction. By arranging the permanent magnets 39aa arranged side by side, a pair of left and right are configured. The permanent magnet 39aa is bonded and fixed to each side of the thrust plates 13a and 13b with an adhesive. Thus, between the permanent magnets 39aa arranged opposite to each other in the axial direction, the magnetic poles are set to be different from each other. Since the main shaft 13 is made of low carbon steel having good magnetic properties, the thrust plates 13a and 13b provided so as to be integrated with the main shaft 13 are also used as the back yoke and the electromagnet target of the permanent magnet 39aa. it can.
The motor stator 39b, which is another part of the motor unit, is arranged without a core so as to face each surface of both the motor rotors 39a in a non-contact manner at a central position between the left and right motor rotors 39a. The coil 39ba is installed on the spindle housing 14 via the motor housing 40. The motor 39 rotates the main shaft 13 by Lorentz force acting between the motor rotor 39a and the motor stator 39b. Thus, since this axial gap type motor 39 is a coreless motor, the negative rigidity due to the magnetic coupling between the motor rotor 39a and the motor stator 39b is zero. The motor stator 39b may have a core, and the main shaft 13 may be rotated by a magnetic force acting between the motor rotor 39a and the motor stator 39b.

The dynamic model of the motor-integrated magnetic bearing device in the compression / expansion turbine unit 5 is formed by rolling bearings 15 and 16 and a support system for these bearings (sensor preload spring 25, bearing preload spring 26, bearing housing 23, etc.). And a spring system in which a synthetic spring formed by a motor unit (the motor 39 and the electromagnet 17) is arranged in parallel. In this spring system, the combined spring formed by the rolling bearings 15 and 16 and the support system of these bearings has rigidity that acts in proportion to the amount of displacement in the direction opposite to the displaced direction, whereas the motor portion. The synthetic spring formed in (1) has a negative stiffness that acts in proportion to the amount of displacement in the displaced direction.
For this reason, the magnitude relationship between the stiffnesses of the two composite springs described above is
Rigidity value of synthetic spring by bearings etc. <Negative stiffness value of synthetic spring by motor unit ... (3)
In this case, the phase of the mechanical system is delayed by 180 ° and becomes an unstable system. Therefore, in the magnetic bearing controller 19 for controlling the electromagnet 17, it is necessary to load a phase compensation circuit in advance. It becomes complicated.

Therefore, in the motor-integrated magnetic bearing device in this embodiment, the magnitude relationship between the stiffnesses of the two combined springs is as follows.
Rigidity value of the composite spring by the bearing etc.> Negative rigidity value of the synthetic spring by the motor unit (4)
It is said. In particular, in this motor-integrated magnetic bearing device, since the axial gap motor 39 is a coreless motor as described above, the negative rigidity value acting on the motor 39 can be made zero, and the motor 39 is high. Even in the state where the load operation is performed and an excessive axial load is applied, the magnitude relationship of the above-described equation (4) can be maintained.
As a result, since the phase of the mechanical system can be prevented from being delayed by 180 ° in the control band, the control target of the magnetic bearing controller 19 can be stabilized even when the motor 39 is operated at a high load and an excessive axial load is applied. The circuit configuration of the controller 19 can be configured as a simple one using proportional or proportional integration as shown in FIG. 3 in the first embodiment.

  In the motor controller 29 shown in the block diagram of FIG. 9, the phase adjustment circuit 41 adjusts the phase of the motor drive current using the rotation angle of the motor rotor 39a as a feedback signal based on the rotation synchronization command signal. The constant rotation control is performed by supplying the motor driving current supplied from the motor driving circuit 42 to the motor stator 39b. The rotation synchronization command signal is calculated according to the output of a rotation angle detection sensor (not shown) provided in the motor rotor 39a. Other configurations in this embodiment are the same as those in the first embodiment. In this embodiment, O-rings may be used as the elastic support members 21B and 22B that support the sleeves 21A and 22A serving as non-contact seals as in the embodiment shown in FIGS.

  FIG. 10 shows still another embodiment of the present invention. In the compression / expansion turbine system of this embodiment, in the peripheral configuration of the sleeves 21A and 22A that are non-contact seals in the embodiment shown in FIG. 8, the rolling bearing retainer members 54 and 55 as in the embodiment shown in FIGS. Is added. Other configurations are the same as those in the embodiment of FIG.

  FIG. 11 shows the overall configuration of the air cycle refrigeration cooling system using the compression / expansion turbine unit 5 in the first embodiment, for example. The motor-integrated compression / expansion turbine unit 5 in the embodiment of FIG. It may be used. This air cycle refrigeration cooling system is a system that directly cools air in a space to be cooled 10 such as a refrigeration warehouse as a refrigerant. It has path 1. In this air circulation path 1, pre-compression means 2, first heat exchanger 3, compressor 6 of air cycle refrigeration cooling turbine unit 5, second heat exchanger 8, intermediate heat exchanger 9, and said turbine unit Five expansion turbines 7 are provided in order. The intermediate heat exchanger 9 exchanges heat between the inflow air near the intake port 1a in the same air circulation path 1 and the air that has been heated by the subsequent compression and cooled. The air in the vicinity of 1a passes through the heat exchanger 9a.

  The pre-compression means 2 comprises a blower or the like and is driven by a motor 2a. The first heat exchanger 3 and the second heat exchanger 8 have heat exchangers 3a and 8a for circulating a cooling medium, respectively, and a cooling medium such as water and an air circulation path in the heat exchangers 3a and 8a. Heat exchange with 1 air. Each of the heat exchangers 3 a and 8 a is connected to the cooling tower 11 by piping, and the cooling medium whose temperature is increased by heat exchange is cooled by the cooling tower 11. Note that an air cycle refrigeration cooling system that does not include the pre-compression means 2 may be used.

  This air cycle refrigeration cooling system is a system that keeps the space to be cooled 10 at about 0 ° C. to −60 ° C., and is 1 atmosphere at about 0 ° C. to −60 ° C. from the space to be cooled 10 to the inlet 1a of the air circulation path 1. Inflow of air. Note that the numerical values of temperature and atmospheric pressure shown below are examples that serve as a guide. The air that has flowed into the intake port 1a is used by the intermediate heat exchanger 9 to cool the downstream air in the air circulation path 1 and is heated to 30 ° C. The heated air remains at 1 atm, but is compressed to 1.4 atm by the pre-compression means 2, and the temperature is raised to 70 ° C. by the compression. Since the 1st heat exchanger 3 should just cool the air of 70 degreeC which raised temperature, even if it is cold water about normal temperature, it can cool efficiently and it cools to 40 degreeC.

The air at 40 ° C. and 1.4 atm cooled by heat exchange is compressed to 1.8 atm by the compressor 6 of the turbine unit 5, and the second heat is increased to about 70 ° C. by this compression. It is cooled to 40 ° C. by the exchanger 8. The 40 ° C. air is cooled to −20 ° C. by the −30 ° C. air in the intermediate heat exchanger 9. The atmospheric pressure is maintained at 1.8 atmospheric pressure discharged from the compressor 6.
The air cooled to −20 ° C. by the intermediate heat exchanger 9 is adiabatically expanded by the expansion turbine 7 of the turbine unit 5, cooled to −55 ° C., and discharged from the outlet 1 b to the cooled space 10. This air cycle refrigeration cooling system performs such a refrigeration cycle.

  In this air cycle refrigeration cooling system, in the turbine unit 5, stable high-speed rotation of the main shaft 13 can be obtained while maintaining appropriate gaps d1 and d2 between the impellers 6a and 7a, and the long-term durability of the bearings 15 and 16 can be improved. Since the long-term durability of the bearings 15 and 16 is improved by obtaining the improvement and the improvement of the life, the reliability of the turbine unit 5 as a whole and, as a whole, the air cycle refrigeration cooling system is improved. As described above, stable high-speed rotation, long-term durability, and reliability of the main shaft bearings 15 and 16 of the turbine unit 5 that are the bottleneck of the air cycle refrigeration cooling system are improved. It becomes possible.

1 is a cross-sectional view of a compression / expansion turbine system according to a first embodiment of the present invention. (A) is an expanded sectional view around the non-contact seal on the compressor impeller side in FIG. 1, and (B) is an enlarged sectional view around the non-contact seal on the turbine impeller side. It is a block diagram which shows an example of the controller for magnetic bearings in the compression / expansion turbine system of FIG. It is sectional drawing of the compression expansion turbine system concerning other embodiment of this invention. (A) is an expanded sectional view of the non-contact seal on the compressor impeller side in FIG. 4, (B) is an enlarged cross-sectional view of the non-contact seal on the turbine impeller side. It is sectional drawing of the compression-expansion turbine system concerning further another embodiment of this invention. (A) is an expanded sectional view of the non-contact seal on the compressor impeller side in FIG. 6, and (B) is an enlarged cross-sectional view around the non-contact seal on the turbine impeller side. It is sectional drawing of the compression-expansion turbine system concerning further another embodiment of this invention. It is a block diagram which shows an example of the controller for motors in the same compression expansion turbine system. It is sectional drawing of the compression-expansion turbine system concerning further another embodiment of this invention. It is a systematic diagram of an air cycle refrigeration cooling system to which the same compression / expansion turbine system is applied. It is sectional drawing of a proposal example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Precompression means 3 ... 1st heat exchanger 5 ... Compression / expansion turbine unit 6 ... Compressor 6a ... Compressor impeller 6b ... Compressor side casing 7 ... Expansion turbine 7a ... Turbine impeller 7b ... Turbine side casing 8 ... Second Heat exchanger 12 ... unit housing 13 ... spindles 13a, 13b ... thrust plate 14 ... spindle housings 15, 16 ... rolling bearing 17 ... electromagnet 18 ... sensor 19 ... magnetic bearing controller 20 ... rolling bearing support 21A, 22A ... sleeve (Non-contact seal)
21B, 22B ... elastic support member 39 ... motor 39a ... motor rotor 39b ... motor stator 40 ... motor housing

Claims (6)

  A rolling bearing and a magnetic bearing are used together, the rolling bearing supports a radial load, the magnetic bearing supports one or both of an axial load and a bearing preload, and the electromagnet of the magnetic bearing is a ferromagnetic body provided on the main shaft. The compressor side impeller and the turbine side impeller are fitted on the same main shaft as the thrust plate, and are generated in the turbine side impeller so as to face the flange-shaped thrust plate made of The compressor-side impeller is driven by the motive power, and has a controller that controls the electromagnet according to the output of a sensor that detects axial force, and is formed by the rolling bearing and a support system of the rolling bearing. The stiffness value of the combined spring is greater than the negative stiffness value of the electromagnet, and Jing is composed of a spindle housing, a rolling bearing support, a turbine side casing, and a compressor side casing, and between the compressor side impeller and the nearby bearing, or between the turbine side impeller and the adjacent bearing, A compression / expansion turbine system comprising a non-contact seal elastically supported by a housing of a compression / expansion turbine unit and forming a seal gap on an outer periphery of a main shaft.   A rolling bearing and a magnetic bearing are used together, the rolling bearing supports a radial load, the magnetic bearing supports one or both of an axial load and a bearing preload, and the electromagnet of the magnetic bearing is a ferromagnetic body provided on the main shaft. The compressor-side impeller, turbine-side impeller, and motor rotor are fitted to the same main shaft as the thrust plate, and the motor rotor is mounted on both sides. A sensor which is disposed between the rolling bearings and which faces the motor rotor, drives the main shaft by a magnetic force or Lorentz force from the motor stator, and detects a force in the axial direction. A controller for controlling the supporting force of the electromagnet according to the output of the rolling shaft, And the stiffness value of the synthetic spring formed by the rolling bearing support system is greater than the negative stiffness value of the synthetic spring formed by the electromagnet and the motor, and the compression / expansion turbine unit The housing includes a spindle housing, a motor housing, a rolling bearing support, a turbine side casing, and a compressor side casing. Between the compressor side impeller and the nearby bearing, or between the turbine side impeller and the adjacent bearing. A compression-expansion turbine system comprising a non-contact seal that is elastically supported by the housing of the compression-expansion turbine unit and forms a seal gap on the outer periphery of the main shaft.   3. The compression / expansion turbine system according to claim 1 or 2, wherein an O-ring is used as an elastic support member that elastically supports the non-contact seal on a housing of the compression / expansion turbine unit.   4. The compression / expansion turbine according to claim 1, 2 or 3, wherein the non-contact seal comprises a sleeve.   The compression / expansion turbine according to claim 4, wherein the sleeve forming the non-contact seal is made of carbon, a copper alloy, or pure copper.   6. The compression / expansion turbine system according to claim 5, wherein the compression / expansion turbine system compresses the incoming air by a compressor of the turbine unit, cooling by another heat exchanger, adiabatic expansion by the expansion turbine of the turbine unit, or compression by a pre-compression unit. A compression / expansion turbine system used in an air cycle refrigeration cooling system that sequentially performs cooling by a heat exchanger, compression by a compressor of a turbine unit, cooling by another heat exchanger, and adiabatic expansion by an expansion turbine of the turbine unit. .

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